In prior systems, there are disclosed a number of arrangements for automatically identifying moving railroad vehicles. These include the use of microwaves, heat sensing devices, color coded light detectors, and alternate reflective and non-reflective variable width area labels. All of them have suffered from being unreliable and not meeting the specifications of the Association of American Railroads Automatic Car Identification (ACI).
Automatic car identification systems have been disclosed in a number of U.S. patents owned by Servo Corporation of America, Hicksville, N.Y. 11802. Representative of these patents are as follows: U.S. Pat. Nos. 3,225,117; 3,569,676; 3,587,050 and 3,646,324. Other U.S. patents in this field are; U.S. Pat. Nos. 3,253,126; 3,443,072; 3,543,007; 3,576,430; 3,610,940 and 3,700,859.
It is thus an object of this invention to provide a highly improved system for reliably and automatically identifying individual objects moving past a fixed reference point.